GB712568A - Improvements in or relating to the production of vinyl chloride polymer and plastisols therefrom - Google Patents

Abstract

Vinyl chloride polymers suitable for use in the production of plastisols are made by emulsifying liquid vinyl chloride alone or admixed with a minor amount of another mono-olefinic monomer and containing a dissolved peroxide polymerization catalyst with an aqueous solution containing between 0.1 and 5 per cent. of an emulsifying agent, homogenizing the emulsion by subjecting it to violent shearing action, heating with agitation at a temperature between 30 DEG and 60 DEG C. to effect polymerization, then heat-treating the aqueous suspension of polymer at a temperature between 90 DEG and 160 DEG C. for a period in excess of 10 seconds but less than that required to agglomerate and coagulate the polymer particles and recovering the polymer. Unpolymerized monomer may be removed from the suspension before heat-treatment. The homogenizing may be effected in a colloid mill or by forcing the emulsion through an aperture, e.g. of not more than 0.03 inch diameter, at such a rate that there is a pressure drop of more than 100 lbs. per sq. inch across the aperture. Specified monomers are vinyl bromide, vinyl formate, vinyl benzoate, vinylidene chloride, methyl acrylate acrylonitrile, methyl methacrylate and styrene. The emulsifier may be sodium or potassium myristate, laurate, palmitate, oleate, stearate, rosinate and/or hydroabietate, sodium or potassium lauryl sulphate, cetyl sulphate, oleyl sulphonate, alkylbenzene sulphonate and/or stearyl sulphonate, Turkey red oil or sulphonated mineral oils, sorbitan monolaurate, monostearate, or mono-oleate, polyethylene glycol esters, the sodium salt of dioctyl sulphosuccinate, cetyl dimethyl benzyl ammonium chloride or lauroyl pyridinium chloride. Catalysts mentioned are lauroyl, caprylyl, stearoyl, benzoyl, acetylbenzoyl, p-chlorobenzoyl and 2, 4-dichlorobenzoyl peroxides, and t-butyl perbenzoate. Plasticizers mentioned for use in plastisols are di-(2-ethylhexyl) phthalate, dibutyl phthalate, dioctyl phthalate, diethyl sebacate and tricresyl phosphate.